1. Field of the Invention
The present invention relates to a camshaft rotational detection structure. More particularly, the present invention relates to a camshaft rotational detection structure configured to detect the rotational angle of a camshaft to which rotation is transmitted from the crankshaft of an engine through a cam sprocket mechanism.
2. Background Information
In DOHC multi-cylinder engines, two parallel camshafts for operating the intake valves and exhaust valves are arranged on the cylinder head of the engine and a sensor is mounted on each camshaft to detect the camshaft rotational angle for the purposes of identifying the cylinders and controlling the valve timing. An example of a mounting structure for this kind of sensor is presented in Japanese Laid-Open Patent Publication No. 2001-329885 (page 4 and FIG. 3). The sensor mounting structure described in that document has a first shaft bearing and a second shaft bearing provided on the camshaft near the cam sprocket mechanism and thrust bearings for restricting axial movement of the camshaft provided axially in front of and behind the first shaft bearing. A shutter (detection target) is also provided between the first and second shaft bearings separately from the thrust bearings, and the sensor is arranged facing opposite the shutter.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved camshaft rotational detection structure. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.